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Airbag code 25 fix

DennisF

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1998
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I have not seen this problem posted, but here's a solution that worked for me. I had my airbag dash light flashing a code 25 and then remain on. When I switched the Passenger Airbag (PAD) switch OFF, the light would remain dark. When I switched the PAD switch ON, the light would light and indicate OFF. Essentially opposite of what you'd expect.

Airbag code 25 identifies a problem with the PAD switch. On my '98 Ranger, the PAD switch is located on the center lower panel next to the ashtray and consists of a lamp, two low tolerance resistors, a magnetic reed SPDT (Single Pole Double Throw) switch, and a magnet mounted on the switch tumbler. After checking all the components individually, I checked the reed switch itself, and found it was resistive in the OPEN position. A SPDT switch is normally OPEN through one contact and normally CLOSED through the other contact. If it becomes resistive in the OPEN position, it means the contacts are sticking from wear or misalignment. There is no mechanical repair of the magnetic reed switch since it is a switch sealed in a glass tube. But..... there is a way to "excercise" the switch. I found that by moving an extremely strong magnet toward and away from the magnetic reed switch you can cause it to move its contacts much more than normally, effectively causing it to rub its contacts clean. You can actually monitor the improvement by connecting a sensitive ohmmeter to the switch while you are "excercising" it.

If you're getting a airbag code 25, try this solution. It's cheap and easy.
 


wankwank123321

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"exercising the switch"

1998 Ford Ranger 2.5L 5-speed.

I have the 25 airbag code and can't seem to solve it. I would really like to know what other ranger drivers are measuring at these terminals.
(The bulb is not burned out, it works just fine)

From my observations of the circuit design I believe it is supposed to be resistive. Switching between the on and off magnet positions only changes the resistance at the output terminals. Now the big question is what are the resistances supposed to be??

I measured mine to be 390 ohms (off) and 665 ohms (on).

The connector going into the switch has four terminals, two of them only go to the bulb with no interface with the "switch". The other two terminals go to the "switch" and resistor combination and only change in resistance thus activating or deactivating the passenger airbag based on the resistance across the two terminals.

If anyone else has these values please share them with me.
 
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wankwank123321

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Update

I found three separate wiring diagrams describing the resistor switch. The resistors are supposed to be 500 ohms (off) and 1000 ohms (on).

My resistors were reading 390 ohms (off)(yellow, violet, brown, gold, (470 ohms)) and 665 ohms (on)(brown, black, red, gold (1000 ohms)). These are much lower than expected or required.

Apparently if this resistances drop too low it will throw a code. Believe it or not resistors go bad and only in one direction, down.... I'm going to pick up some new ones in the morning and solder them in place and see how that goes.
 

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